Tunneling Definition and 268 Threads

I have always been curious about what would happen to the gravity at the center of the earth. After some googling I found some neat stuff. So IF it was possible to endure the heat and pressure to get there (impossible) it would feel weightless. So that answered my question but then I read it...

Homework Statement I don't understand how a battery will affect the electron's wavefunction. Homework Equations The image I've attached is something like my problem. The Attempt at a Solution I know without a battery, the wavefunctions of an electron from the right side and...

Homework Statement A scanning tunneling microscope (STM) can precisely determine the depths of surface features because the current through its tip is very sensitive to differences in the width of the gap between the tip and the sample surface. Assume that in this direction the electron wave...

Homework Statement A scanning tunneling microscope (STM) can precisely determine the depths of surface features because the current through its tip is very sensitive to differences in the width of the gap between the tip and the sample surface. Assume that in this direction the electron wave...

Homework Statement Two copper conducting wires are separated by an insulating oxide layer. This layer acts as a square barrier of height 10 eV. Estimate the transmission coefficient for penetration by 7 eV electrons (a) if the layer thickness if 5 nm and (b) if the layer thickness is 1 nm...

So i was messing around with a wax prism and a microwave emitter. So I have an emitter and a detector and the microwaves are being shot straight across to the detector. But when I place a Wax prism in between it stops getting the signal . But then when we place a second wax prism next to it, it...

Hello, I'm having trouble imagining a specific portion of a homework problem. Heres the problem: "Consider a ligand stabilized gold nanoparticle. The gold nanoparticle itself can be considered as “box” and the ligands as the “walls”. If the de Broglie wavelength of the gold...

Taken from an entirely empirical standpoint, the true nature of Consciousness should be the Chinese room argument, that it is nothing but an illusion created by the interactions of billions of neurons, electrical and chemical signals. Supposedly this would disprove "The Human Soul" and...

Hello, I'm following an introductory course in modern physics. So I understand there's a chance the particle appears on the right side of the barrier, and this has been experimentally verified. Now I was wondering: can the particle also appear in the barrier? If so: is this directly...

Hey there, I'm pursuing a degree in Msc. Nanoscale science, and I've been studying about Scanning tunneling microsopes that use Quantum tunneling to study the surface struture of materials. My question is: What is the maximum distance between the surface that's been studied, and the STM tip...

Alright, so there's definitely a lot of Sci-Fi hype about Entanglement. I'm sort of hoping the experts on the subject can set this straight. Question: Could it actually be used to transfer information instantly from one point to another, seemingly providing FTL communication? And second, does...

How close do two room temperature deuterium nuclei need to be to each other to have a one-in-a-quintillion chance of "tunneling" into each other so that the nuclear forces bind them together despite the repulsive effect of the positively-charged protons?

I've heard that Sun is not hot enough to sustain thermonuclear fusion at the level we observe. Instead, the solar output relies on quantum tunneling of protons through their natural repulsive barrier. Might this same effect be useful in obtaining controlled thermonuclear fusion? It seems to me...

Homework Statement The work function (energy needed to remove an electron) of gold is 5.1 eV. Two pieces of gold (at the same potential) are separated by a distance L. For what value of L will the transmission probability for an electron to cross from one to the other be T ≈ 10-3? Assume...

So I've been reading up on some quantum tunneling. It seems as though everything I read on it only conveys an elementary view on the matter, as if their target audience was the general public. I am here to gain a more sophisticated understanding of this concept. As I currently understand...

Howdy, Can anyone explain qualitatively (without using any maths) why a particle with a smaller mass has a greater probability of tunneling through a potential barrier than another particle with a larger mass but of the same total energy? Thanks

Is it possible to achieve commercially viable nuclear fusion in purely electrostatic quantum tunneling way?What should be voltage of electrostatic field (no particles bombarment) to overcome Coloumb bareer and make tunneling fusion probable?

It is a theory, but quantum computing could most likely out perform classical computers. In this regard, would it limit the progression of AI if it could go beyond classical computing? Assuming that quantum computing catches up and out performs classical computers, will computer engineers have...

Homework Statement Suppose that a ball is tossed at a wall; what is the probability that it will tunnel through to the other side? The mass of the ball is 0.14 kg, the width of the wall is a = 0.2 m, and the one who tossed the ball was deadly tired, so that the ball is tossed only weakly at...

Good day, everyone! Lately I faced the necessity of solving a problem from a field I know literally nothing about. So I just made an online research but without success. Any help (hints, good sources, relevant equations) would be greatly appreciated! Homework Statement Gold nucleus (Au...

Friends, I am trying to consider an impurity which can be viewed as a 1D resonant-tunnelling problem. I gather that the transmission coefficients TL and TR will decay exponentially from the impurity to the edges of the barrier. However, I am unsure how to predict how the peak & area of T(E)...

I'm calculating the band-to-band probability using the WKB approximation given by T=exp(-4*lamda*sqrt(2*m*Eg^1.5)/(3*q*hbar*(deltaPhi+Eg))). I am wondering which unit of the plank constant is used here? The one in J-s which is 6.62e-34 or in eV-s which is 4.13e-15? However, the former one...

can anyone tell me what's the formal analogy between electron tunneling in terms of quantum mechanics and electromagnetic waveguide modes at frequencies below cutoff ?

On 8/16/09 a alxm wrote... Macroscopic objects have a quite definite location, and do not tunnel to any appreciable extent. Another way to say it is: The location of a macroscopic object is only a little bit random, and the probability of tunneling is very very small. Is that correct...

I've recently started trying to use this technique, but I've had some difficulties I can't figure out how to overcome. We make our own probe tips from a very small length of 30 gauge wire, and they seem to be of decent quality. We've tried to image a layer of graphite, a gold surface...

Hey everyone, For my a research project on quantum tunneling I have to tie in math somehow, so I was wondering if anyone could help me learn to calculate the probability of a wave (preferably like an electron or electrical voltage) of some sort passing through a rectangular barrier, which is...

I have no idea how to solve these problems. Picture is attached. An electron with energy E is incident on a barrier of height U0 and total width L. It enters the barrier at x = 0, from the left. 1) For an electron with energy E = 6 eV and a barrier of height U0 = 12 eV, at what penetration...

Hi, I'm doing a research project for my high school physics class. I originally set out to research touch screens but was disappointed with how simple the mechanics of the iphone are (or at least the basic physics of it). I continued researching and found that soon Quantum Tunneling may be...

I'm trying to find the experimental evidence for quantum tunneling during a fusion reaction. Take the simple D + D -> T + P reaction. I know that the energies required to make this happen are much lower in actual experiment than what would be predicted by Coulomb's model of the electrical...

I was on another forum and somebody was talking about quantum tunneling and that walking through walls was not impossible. Just highly improbable; the probability of it happening is older than the universe. Some reason it blew my mind away, even though not much was said. Anyone have more insight...

Hello, With regards to a Youtube video- Spin polarized tunneling - video #10: , could some one familiar with electronics provide a circuit or diagram for this to work? Also what type & size of barrier could be used? This should be fairly easy for anyone familiar with electronics, so any help...

How is the wavefunction within a rectangular potential barrier an evanescent wave? I thought an evanescent wave was exponentially decaying. If you take x->infinity for the following function for E<V, one of the terms goes to 0 but the other term goes to infinity, so the wavefunction will go to...

I was wondering about the effect of tunneling of particles in a magnetic field. Classically, a charged particle will whiz around in a circle in a magnetic field, and barring any interruptions, electric fields or gradients in the magnetic field, it'll stay centered around the same magnetic...

I have 2 questions... I was told that the transmutation of Li-7 to Be-8 by proton collisions at energies below the classical barrier verifies the QM description of the weak interaction cross section. Firstly, I found the leap in logic very confusing - does the weak force have a role in...

This may be a bit of a silly question, but I'm wondering if it is feasible to design a freshman level lab experiment using a STM? For example, let's say the lab is simply intended to give the students a better appreciation of how a STM operates within the framework of quantum mechanics, with the...

Hi. Firstly, can a particle every be found within the potential barrier? I've used the search function to look for an answer for this question, but I didn't really get anything conclusive. However, from what I gather, since there is a probability associated with it being 'found'(meaning it...

Would it be possible to tunnel directly to the center of the Earth using currently available means, or would the centrifugal effect cause you to unwittingly continue on toward the nearest point on the surface so that you emerge near the point where you began without ever having gone beyond a...

Homework Statement Suppose a tunneling current in an electronic device goes through a potential-energy barrier. The tunneling current is small because the width of the barrier is large and the barrier is high. To increase the current most effectively, what should you do? a. Reduce the width...

Homework Statement Consider the harmonic scillator potential perturbed by a small cubic term, so that V(x) = \frac{1}{2}m\omega^{2} (x^{2} - \frac{x^{3}}{a}) if a is large compared to the characteristic dimension (\hbar /m\omega)^{1/2}, the states will all me metastable, since there can be no...

Can someone give me either an explanation or a link to explain why tunneling cannot carry information greater than the speed of light? I understand why entanglement cannot, but this is not the same thing

Homework Statement A particle of mass m is incident on a planar barrier which we represent by a potential V(z)=\lambda\delta(x). If the energy of the particle is E, and the incident velocity makes an angle \theta with the z axis, what is the probability that the particle will penetrate the...

Homework Statement An electron of energy E = 2.10 eV is incident on a barrier of width L = 0.67 nm and height Vo = 3.10 eV What is the probability that the electron will pass through the barrier? Homework Equations I know that T=Ge^-2KL. K=2pi*sqrt((E-Uo)/1.505eVnm^2))...

How can we create a potential barrier? And how does it exactly acts as barrier in electron transfer?

From what I read, there is an extremely small probability of one going through a solid wall, according to QM. The chance is so small you might have wait a few lifetimes, or more of the universe to observe it. But how about going very shallowly into the wall? Let's say a few angstroms (Å)...

On pages 23 & 24 of the book Superforce by Paul Davies - The unusual occurances of electrons or other particles as they approach a barrier are described. I would like to know what devices are used in these experiments? What device shoots out electrons or other particles in a single stream...

The probability of finding the particle inside the wall is non-zero, What happen if we do find the particle is inside the wall, would that violate energy conservation? since total energy is smaller than the potential energy of the wall

Wave packets / the wave function is described as the probability density function of a particle, implying that the particle exists exactly at any 1 location at a time according to its associated wave function. This does not make sense to me on many levels, and it seems inconsistent with quantum...

Hi! I have a physics presentation tomorrow where I have to explain how a scanning tunneling microscope works. I also have to explain what quantum tunneling is and how it is used in a scanning tunneling microscope. I've done some research on the internet and I think I have a basic grasp of...

Homework Statement Alpha decay typically involves an alpha-particle of 5-6Mev. How can this be explained using quantum mechanics? Homework Equations The Attempt at a Solution I think I need to work out the potential barrier and then work out how much KE an alpha particle has...

Tunneling effect in Supercapacitors ? Hi everyone! This is my first post … so please bear with me! My question concerns the double layer developing within every supercpacitor / EDLC http://en.wikipedia.org/wiki/Electric_double-layer_capacitor" Considering the interface electrode –...